基于冻融循环试验的季节性冻土区边坡稳定性分析

内蒙古包头地区属于典型的季节性冻土区,冻胀和融沉是冻土危害产生的主要原因,也是人们面临的重大难题。通过建立非饱和粉砂土黏聚力、内摩擦角与冻融循环参数之间的定量关系,探索冻融循环对粉砂土抗剪强度的影响规律。通过对不同含水率、不同干密度的土样进行不同次数的冻融循环分析并总结其变化规律,研究发现:不同干密度、不同含水率的土样,黏聚力都会随着冻融次数的增加不断减小;内摩擦角会随着冻融次数的增加逐渐趋于稳定,波动的幅度在5°之内;抗剪强度的变化趋势受黏聚力的影响较大。最后,用岩土工程软件进行有限元分析,利用折减系数法计算边坡的安全系数,以此为包头地区季节性冻土的研究提供更好的理论基础。

Stability Analysis of Seasonal Frozen Soil Slope under Cyclic Freezing and Thawing Test

Baotou city of Inner Mongolia is a typical region with seasonal frozen soil where frost heaving and thawing is the main cause of frozen soil damage. The influence of cyclic freezing and thawing on the shear strength of silty soil was investigated by establishing the quantitative relationship of cohesion and internal friction angle against freeze-thaw cycle parameters. Moisture content, dry density, and number of freeze-thaw cycle were controlled in the test. Results showed that cohesion decreased steadily as cyclic freezing and thawing proceeds regardless of dry density and moisture content of soil specimen; internal friction angle stabilized with the proceeding of cyclic freezing and thawing, fluctuating within a range of 5°; shear strength of silty soil was mostly affected by cohesion. In addition, finite element analysis was carried out with geotechnical software, and the safety factor of slope was calculated by the reduction coefficient method. The research is expected to offer better theoretical basis for researching the seasonal frozen soil in Baotou.